Escape From The Dark (1977 Movie)

Escape From The Dark Description:

In Disney’s Escape From The Dark, when the owner of a coal mine pit decides to destroy the ponies and replace them with steam engines, three children hatch an ingenious plan to rescue the animals. After they’re caught “horsenapping,” all looks lost when the mine explodes, trapping the miners below, and only the ponies can save them. Will the town decide to save the ponies?